Step 1 — Relevant industry

ENI S.p.A. is an integrated oil and gas company with upstream exploration and production as a major activity, plus downstream/refining/marketing and other energy businesses. Among the provided methodologies, the closest fit is Oil And Gas Exploration And Production. For the debt-to-EBITDA calculation, I apply the baseline S&P-style corporate adjustments using the available reported data.

Step 2 — Estimate Adjusted_Debt

Use year-end 2022 balance sheet values, presented as 2023-01-01.

Debt components:
- Short-term borrowings: €4,446 million
- Current portion of long-term borrowings: €3,097 million
- Long-term borrowings: €19,374 million
- Current lease liabilities: €884 million
- Noncurrent lease liabilities: €4,067 million

Reported borrowings excluding leases:
= 4,446 + 3,097 + 19,374
= €26,917 million

Lease liabilities:
= 884 + 4,067
= €4,951 million

Gross debt including leases:
= 26,917 + 4,951
= €31,868 million

Eligible cash:
- Cash and cash equivalents: €10,155 million

Assume no additional pension deficit, guarantees, hybrid debt portion, or other debt-like adjustments are quantifiable from the provided facts. Although ENI has perpetual subordinated bonds in equity, the year-end balance is not directly provided in the statement of financial position facts, so I do not add a hybrid debt portion.

Adjusted_Debt:
= 31,868 - 10,155
= €21,713 million

Step 3 — Estimate Adjusted_EBITDA

Reconstruct EBITDA from operating profit by adding depreciation, amortization, impairment, and write-offs.

Given:
- Profit/loss from operating activities: €17,510 million
- Depreciation and amortisation expense: €7,205 million
- Impairment loss/reversal recognized in profit or loss: €1,140 million
- Write-off of tangible and intangible assets: €599 million

Adjusted_EBITDA:
= 17,510 + 7,205 + 1,140 + 599
= €26,454 million

No further quantifiable S&P adjustments for leases, pensions, guarantees, or proportional JV EBITDA are provided. Share of profit/loss of equity-accounted investments is below operating profit and is not included in this EBITDA reconstruction.

Step 4 — Adjusted_Debt / Adjusted_EBITDA

= 21,713 / 26,454
= 0.8208

Rounded to two decimals:

<answer>0.82</answer>